Disk Utility may be unable to modify (or erase) a disk after it is formatted as NTFS in Microsoft Windows XP. All of the options in Disk Utility may be dimmed (”grayed out”). The drive may also appear with a Write Status of “Read Only”. Note: Before erasing a disk, you should back up any important files on it to a different disk.

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Mac OS X: Disk Utility – All options dimmed for a disk that was formatted as NTFS in Microsoft Windows XP

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